Hardness-testing machine and method of testing hardness



Get. 18 1927.

H. M. GERMAN HARDNESS TESTING MACHINE AND METHOD OF TESTING HARDNESS Filed May 29, 1926 INVENTOR 1/ AM a be operated atdiiferen't times or by diifer-.

with though the material is tested at difierent. times under like conditions with respect to- Iwill lie-obvious that they involve an inaccu- 'curate measurement offlhardness by defor of my broader claims.

1 B in ll testing apparatus as Patented" a. 1a, 1927.'

PATENT OFFICE.

nowmn I.- cum, orscamon, rnmzsnvanm muss-marine 1140mm: m mi'rnon or 'rnsrme EABDIN'ESS.

Application fled Kay 29,

At the present time it is customary to test metals for hardness in accordance with threerecognized methods. These methods are ordinaril referred to as the Brinell', Rockwell and scleroscope. Of these three, the Brinell is perhaps the most commonl used. The present invention relates broa 1y to improvements in testing machines, and more art-icularl' testing. machinesof the Brine type, an to im rovements methodsiof testing in accor ance therewith. a Itis well recognized that the Brinell test determines hardness-by deformations, but there area great many. factors entering nto" the testing. and the same apparatus may ent en eers on the. same piece of material ifierent results. ThlS 1s true even.

temperature and thelike. While the variations between successive tests'are small,;1t'

racyjf which it is highly desirable to overcome." The present invention has for one of its objects the provision of a testmg apparaltus and method of testing by de ormation of such nature that success ve tests under like conditions will give more nearly uniform readings, thereby enabhng a more acmatione-to be obtained} 1 In the accompanying draw1n there-1s shown for' ,of lllustratio'n only a ferredf' embodiment. of my inventlon, 1t understood that the draw ngs "do not define theiimits of 'my invention, as changes in 1 the construction and operation disclosed therein may be without departing fr spirit of my jniventlon or the scope In 'the drawn.

Figure is'.' a side elevational view'ofa test machine constructed in accordance with fiie present invention; and

- 2 is :a vertical sectional new on a i e 11:11 ,of Figure looking in the direction of. the arrows...} I

ed -'at the .fpresent fime gthe possibilit f.- error in the making of successlverea ngs arises largely from the difference in speed.

ofconducting the tes'tor the difierencc in time utilized in. successive tests inbuilding up the desired operating pressure. --I or steel and hardermetals, k lqt' lever 13- through a 1i nectionsbetweeni these .knife edged bearings reducing 1888. Serial Ilo. -112,570.'

' grams is the standard pressure utilized while for softer metals such as lead and babbitt a more moderate pressure is used.

-the .pump' or the screw are operated at a comparatively high speed, the inertia of the parts which must be moved plays an im' ortantpart and-a considerably deeper in entation is obtainedunde'r such conditions than under conditions in which a similar test 1s conducted-s ore slowly. The present -1nvent1on eliminates to a very large extent made not only under like' conditions with respect-to factlnrs heretofore taken intoconsideration, but under like conditions with respect to applied pressure and duration of apparent that in all cases the period during which 'thepressure is applied should be longeno'ugh to permit the parts to reach an material be tested, the support being ver- "tlcally. ad ustable, as bymeans of a screw 4- and coodperating hand wheel 5. Carrie by the frame in opposition to the support 3" 1s a plunger 6' carrying at its .lower end .a material engaging member 7 of known characteristics; In accordance with standard conditions employed at'sthe present tlmethis member may be in the cm of a ball, although a, cone or other shape' maybe efiectivel ;utilized. The I plunger 6 cooperates with ife edged bear- I 1ngs8 on a lever'9. This lever preferably has a pivotal bearing of the knife edge type 10 by which it issup {2. At its other end t e lever;9 is connected to a second lever 11 through a link 12, and

rted from the frame connected to a third It. .;All of the conparts'may comprise "'th purpose of the lever -'11 is similaglly or friction and insuring greater ac; By reason of'th system of lever's disclosed herein it will apparent that a comparatively largemovernentof the outer end of the lever 13 'yesagromparatively small movement of t ejmaterial engaging member, but at. the same time increases the curacy.

the human element. and provides a method of such nature that successive tests may be the: applied pressure. It will of course be lever 13 and its associated parts.

effectiveness of any load applied to thev member 13.

In accordance with the present invention I preferably apply a load by providing projecting bearings 15 on the outer end of the number of weights will vary the appliedpressure by predetermined amounts. In order to compensate accurately for any nonuniformity as to weight, or the like, each of the links 16 may carry a compensating cup 18 for the reception of lead shot in variable quantities.

With the construction of the character described, it will be obvious that upon releasing the outer end of the lever 13 the weights applied to the links will operate to impose a predetermined and definite ressure on the material engaging member It is desirable, however, in order to insure uniformity of application of the pressure to prevent the sudden dropping of the lever 13 under such conditions that a blow is trans-' mitted to the material. For uniformly releasing the weight for successive tests I may provide an operating pitman 19 pivotally connected to the outer end of the lever 13 and guided at its intermediate portions in bearings 20. At its lower end the pitman carries a roller 21 ada ted to cooperate with a cam 22. This cam has an operating face which may be divided into three parts. Assuming rotation of the cam in the direction indicated b the arrow in Figure 2, the portion of t e cam included by the angle A will be effective for gradually lowering the weights to permit them to pull the material engaging member into contact with the material with a slow definite movement. By

the time the' roller 21 reaches the end of the portion included by the angle A the member 7 will be in engagement with the material. During rotation of the cam through the next 180 the portion of the cam included by the angle B will be ineffective for exerting any sustaining influence on the pitman 19 and consequently the During this eriod therefore a constant and redetermlned load or gravity pull will exerted on the lever 13 and transmitted thereby to the material engaging member. By reason of this constant and predetermined applied pressure, successivetests under like conditions will give uniform readings of a character heretofore not obtainable. The speed of operation of the cam will obviously be such that during the travel thereof through the angle B suflicient time will be given to permitthe material and material engaging member to come into equilibrium. Thereafter, the portion of the cam included by the angle C will be effective for gradually raising the weights and relieving the pressure.

The cam ma be 0 erated in any desired manner, but I have f und advantageous results are obtained by mounting it on an axle 23 driven by a worm wheel 24. This worm wheel may in turn be driven by a worm 25 operated through a reducing gear train 26 from a motor 27. The gear reduction will preferably be such that althou h the motor may operate at a comparative y high speed, for example, 1800 R. P. M., the worm will operate at a com ratively low speed, for example, 150 R. M. Under such conditions the pitch of the worm and worm wheel would be such that the worm wheel and cam would be given one revolution for each 150 revolutions of the worm. This would provide an operating condition such that approximately 15 seconds would be devoted to lowering the weights, 30 seconds to the test period and 15 seconds to returning the parts to normal conditions. With such a gear reduction, a slight variation in the speed of the operating motor produces an almost negligible variation in the speed of operation of the cam. In any case, however, the contour of the cam portion embraced by the angle A is such as to insure a gradual lowering of the weights and application of the pressure so that variations in operating speed do not vary the accuracy of the results obtained. It will be found apparent to those skilled in the art that the times and speeds referred to herein are illustrative only, it being appreciated by me that the times and speeds may be varied within comparatively wide limits with different materials while maintaining accurate results.

The motor ma be provided with a control of known 0 aracteristics such that at the conclusion of each revolution of the cam 22 the motor circuit will be stopped with the parts substantiall in the position illustrated in Figure 2 rea y for a succeeding test.

Certain advantages of the resent invention arise from the provision o a testing machine operable for determining hardness by deformation in which the'testing pressure is obtained through ,gravity ztby' means of weights gradually movedintooperative position. Other advantages ,of'the invention arise from a method of yeting" hardness of materials by deformatiop under such conditions that successiite tests give uniform re- 5111138. I. v i I'claim:

1. In the .metholgoi testin the hardness of materials bydeformation, the steps com- Ill pzising providing a material enga ing mem-. r, gradually producing a pre etermined definite. relative movement between said member and the material to be treated to bring the same together, exerting a predetermined and constant gravity pull on said member to cause it to penetrate the material being tested an amount determined by the hardness of such material, and then returning said member to its original osition.

2. In the method of testing t e hardness of materials by deformation, the steps comprising providing a material engaging member, producing gradual relative movement between such member and the material to be tested to bring the same' into engagement, exerting a predetermined and constant pressure by gravity on said member throughout a fixed period to cause it to penetrate the material being tested an amount variable with its hardness, and then'returning said member to its original position.

3. In the method of testing the hardness of materials, the steps comprising providing a weight controlled material engaging member, and gradually increasing the effectiveness of the weight on said member at a predetermined definite rate untilthe weight becomes constant, maintaining the weight constant until the parts come into equilibrium, and then returning the weight to its original position.

4. In the method of testing the hardness of materials, the steps comprising providing a weight controlled material engaging member, and gradually increasing the effectiveness of the weight on said member at a predetermined definite rate until the weight becomes constant, maintaining the weight constant for a fixed period, and then returning the weight to its original position.

5. In the method of testing the hardness of materials, the steps comprising providing a weight controlled material deforming member, and gradually increasing theefiectiveness of the weight on said member at a predetermined definite rate until equilibrium I between the member and material being tested is reached whereby the deformation of said member is determined entirely by the effect of gravity on said welght.

6. In a testing apparatus, a material engagln member, a weight of a fixed value for e ectlng movement of said member, and

means operable at a predetermined speed only for gradually releasing said weight and thereafter raising the samein timed relation for definitely controlling the actual testing period.

7. In a testing apparatus, a material engaging member, a weight of a fixed value for effecting movement of said member, and

cam. means operable at a predetermined by the efiect of said weight on said member is increased, cam means for gradually increasing the efi'ect of said weight on said member, and means for operating the cam at a predetermined definite rate.

10. In a testing machine, a material engaging and deforming member, a weight of fixed characteristics operable on said member, and motor operated means. normally holding said weight in inoperative position,

said means being operative for controlling both the descent and elevation of said weight throughout the entire distance of movement 7 thereof.

11. In a testing machine a material engaging and deforming member, a Weight of fixed characteristics operable on said memher, and motor operated cam means normally holding said weight in inoperative position, said means being operative for controlling both the descent and elevation of said weight throughout the entire distance of movement thereof.

In testimony whereof I have hereunto set In hand.

y HOWARD M. GERMAN. 

